The confirmed transmission modes of SARS-CoV-2 include respiratory droplets and physical contact, but it is called into question also the contact with contaminated surfaces. The Research Letter of Luo et al1 reports a cluster-spreading event in which a patient with SARS-CoV-2 may have transmitted the virus to 8 other healthy individuals via bathing in a public bath center. However, there was a lack of detail regarding the transmission routes of the patients in the bath center.
Recently, an article published in the NEJM2 analyzed the SARS-CoV-2 resistance on certain surfaces.
The paper2 confirmed that also SARS-CoV-2 is quite stable on surfaces like stainless steel, being detected up to 48-72 hours after application.
In this case, it may be also possible that some individuals have been infected by touching common surfaces contaminated by a SARS-CoV-2 positive patient, such as the taps in the bathrooms.
By turning the knob, especially after coughing, sneezing or cleaning with toilet paper (stool/anal swabs can contain SARS-CoV-2),3,4 everyone deposits germs on it. After washing hands with soap, closing the knob the germs are taken back. Every follower paradoxically collects them by implementing a "preventive" measure, maybe before bringing food into the mouth or changing contact lenses.
The CDC recommends to clean and disinfect high touch surfaces,5 but it is unrealistic to do so after each tap use.
Knob taps are critical points in the transmission chain: instead, new toilets should install long elbow-levers, or at least short levers, provided people are educated to close them with the forearm or the cut of the hand, foremost in high-risk communities (retirement homes, prisons), but also in workplaces, schools and families. Meantime, existing knobs must be closed with disposable paper towel wipes, or with toilet paper sheets.

In December 2019, a novel pneumonia named coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan, China, and has since spread to 25 countries. Current reports show that SARS-CoV-2 is closely related to severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV)1,2 and that it has a greater transmissibility than other coronaviruses. The confirmed transmission modes of SARS-CoV-2 include respiratory droplets and physical contact, and the incubation period for the virus is approximately 3 to 7 days, but it can be as long as 24 days.3 In this case series, we report a cluster-spreading event in Huai’an (700 km northeast of Wuhan) in Jiangsu Province, China, in which a patient with SARS-CoV-2 may have transmitted the virus to 8 other healthy individuals via bathing in a public bath center.

Methods

Data were collected from Huai’an No. 4 Hospital of Jiangsu Province, China. A total of 9 patients who had been to the same bath center were hospitalized and enrolled from January 25, 2020, to February 10, 2020. Throat swab samples were collected, and SARS-CoV-2 was detected using a quantitative reverse transcription–polymerase chain reaction assay. Computed tomography and hematological examinations were performed for auxiliary diagnoses. Data were analyzed with Prism version 7.00 (GraphPad). This study was approved by the ethics committee of Huai’an No. 4 Hospital, and written informed consent was obtained from all patients. This study followed the reporting guideline for case series. No prespecified threshold for statistical significance was set.

Results

The bath center for men was approximately 300 m2, with temperatures from 25 to 41 °C and humidity of approximately 60%. It contained a swimming pool, showers, and sauna. The first patient (patient 1) had traveled to Wuhan. He went to the bath center and showered on January 18, 2020. He started experiencing a fever on January 19, 2020, and was diagnosed with COVID-19 on January 25, 2020. The next 7 patients showered, used the sauna, and swam in the same center on January 19 (patients 2, 3, and 4), January 20 (patient 5), January 23 (patients 6 and 7), and January 24 (patient 8). The symptoms associated with COVID-19, including fever, cough, headache, and chest congestion, appeared between 6 and 9 days after visiting the bath center. Patient 9 was working in the bath center and experienced onset on January 30. Infection in all patients was confirmed by positive reverse transcription–polymerase chain reaction assay results (Figure).

Computed tomography examinations were performed, and the ground glass opacities were observed in all 9 patients. As of February 10, 2020, no patients required respiratory support.

Discussion

Previous studies have demonstrated that the transmission rate of a virus is significantly weakened in an environment with high temperature and humidity.4 However, judging from the results of this study, the transmissibility of SARS-CoV-2 showed no signs of weakening in warm and humid conditions. We noticed a clustered case occurring in a public bath center with high temperature and humidity. A total of 8 individuals who used or worked in the bath center experienced symptoms within 6 to 9 days of their visit to the center, suggesting that SARS-CoV-2 could spread and cause infection in such an environment. The transmission routes may also be respiratory droplets or contact, but our results suggest that the cluster transmission of SARS-CoV-2 can still arise in an environment with high temperature and humidity. These results provide a potential epidemiological clue for this novel coronavirus. This study was limited by a lack of detail regarding the transmission routes of the patients in the bath center.

Author Contributions: Drs Luo and Zhang had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Drs Luo, L. Yao, and Zhang contributed equally as co–first authors. Drs Wang and Shen contributed equally as senior authors.

Funding/Support: This study was supported by the National Natural Science Foundation of China, with award 81772585 to Dr Wang, award 81972739 to Dr Luo, and award 81972738 to Dr Zhang and the Key Laboratory Projects of Huai’an, with award HAP201804 to Dr Wang and award HAP201910 to Dr Zhang.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.